int testLinkRing(LinkNode* pHead) {
    LinkNode* lk1 = pHead;
    LinkNode* lk2 = pHead;

    while(t1->next && t2->next) {
        t1 = t1->next;
        t2 = t2->next->next;
        if(NULL == t2) {
            return 0; //无环
        }
        if(t1 == t2) {
            return 1; //有环
        }
    }
    return 0;
}